Serving all aspects of commercial horticulture

Plant health care and IPM practices

by Sanne Kure-Jensen

“Plants are healthiest when grown in their ideal environment. The majority of the landscape plants and trees are planted too deep, not watered properly, improperly fertilized and over-mulched,” said Randy Zondag, commercial horticulturist and director of Ohio State University Extension.

“Pest problems are usually a response to plants under stress. If pest issues occur, identify the pest and select the most effective method(s) to control them,” Zondag continued. He spoke on “Plant Health with IPM” at the 2014 RINLA Winter Conference. Zondag offered tips for predication, scouting, timing and proper treatment coverage.

Zondag recommended growers and retailers explain and advocate for their growing practices. “We grow a product that sequesters carbon. If these plants are cared for and grow to maturity, they will have a dramatic impact on storm water and carbon issues. We need to tell our story better,” Zondag continued.

Zondag urged everyone to plant for 60 to 70 years, not just five to seven years — the average life of many urban street trees. A tree does not have a major impact until it reached at least 15 years of age. You need to “do it right the first time. You can’t fix your mistakes when the plant is dead,” said Zondag.

“Soils and growing mixes are a biological community. Encourage the good bugs and they will fight the bad bugs,” said Zondag. Organic matter like composted mulch is critical to healthy soil. Soil should be fertile, friable and moist, not compacted, soaked or dry. “Create the right environment and the biologicals will come,” said Zondag.

Plant Health Care

Zondag told landscapers, “You’ll become plant doctors. Explain why you do what you do and charge more as a professional plant caretaker and educator.” Teach customers to plant correctly and provide proper plant health care. A simple soil test will tell us how much or which nutrients and lime to apply. Do not over-fertilize plants. This can increase risks of pest infestations and diseases. Most plants need a quick-release nitrogen-rich fertilizer in the fall and a slow-release, gentle fertilizer as the spring flush winds down. Apply phosphorous only as soil tests indicate, June through August. Later applications are unneeded. They are likely to run off causing downstream water pollution and algal blooms.

Teach customers to be your plant care partners. They can help with scouting, pruning and maintenance. Customers will understand and respect what you do. Build and maintain a relationship with customers.
Call your customers after a treatment and ask, “How did my treatment do?” Better yet, make a follow-up visit.

IPM

“Integrated Pest Management (IPM) is planting the right plant in the right place followed by using a combination of cultural, biological and chemical practices and treatments. “IPM uses the best and most sustainable methods to grow plants and make a profit,” said Zondag

Predication

Keeping good records of plant phenology helps predict pest outbreaks when you are scouting. Track spray treatments and follow label recommendations for treatment rotations to minimize risk of resistance. Use companion and host plants for biological and predatory insects. Have beneficials on-site before a pest outbreak reaches critical levels.

Scouting

Train customers and staff to take “cultural walks” around customer sites. If you learn to match key pests to key plants, this will become your guide when looking for pests. Note risky plants and revisit regularly. Scout for and identify pests, watch for treatment thresholds. Be sure to follow-up with post-treatment monitoring visits.

Use handbooks and the Internet to identify insect pests. Learn their lifecycle stages of maximum destruction and most effective control. Use pest fact sheets to educate staff and customers. Tell them, “this is the pest and these are the treatment options,” said Zondag. Try the simplest, least toxic modes of control first. Consider pruning out diseased branches, insect webs or egg masses. Utilize natural predators where applicable. Spray when other approaches do not work and when customer thresholds are reached, not before.

Zondag said, “More volume does not equal better coverage.” In many cases, as much as 40 percent of spray treatments end up on the ground and 10 to 15 percent in spray drifts. Only the remainder reaches its target and stays where it should. Zondag said the average applicator uses and pays for 2 – 12 times more chemical than needed.

Remember to calibrate sprayers every fall. Calibrate again when changing nozzles, pressure gauges or equipment tires. Invest in the right nozzles, get ideal coverage, spray less and save money. Use the right amount of surfactant to avoid phyto-toxicity. Test spray patterns with orange dye or water sensitive paper. Zondag said research reveals the ideal droplet size is 250 – 300 microns.

Be cautious with spray drift. Be sure to follow all worker-protection standards. Be sure to train staff and follow all cautions. Zondag said, “the public is running scared of pesticides.”

New Technology

Laser-guided sprayers use a sensor to turn on individual spray nozzles only where the plants are. They will not spray spaces between or above plants. This equipment quickly pays for itself in unused spray products.

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